Delegating ZFS Permissions (Examples)

Example 9-1 Delegating Permissions to an Individual User

When you delegate create and mount permissions to an individual user, you must ensure that the user has permissions on the underlying mount point.

For example, to delegate user marks create and mount permissions on the tank file system, set the permissions first:

# chmod A+user:marks:add_subdirectory:fd:allow /tank

Then, use the zfs allow command to delegate create, destroy, and mount permissions. For example:

# zfs allow marks create,destroy,mount tank

Now, user marks can create his own file systems in the tank file system. For example:

# su marks
marks$ zfs create tank/marks
marks$ ^D
# su lp
$ zfs create tank/lp
cannot create 'tank/lp': permission denied

Example 9-2 Delegating create and destroy Permissions to a Group

The following example shows how to set up a file system so that anyone in the staff group can create and mount file systems in the tank file system, as well as destroy their own file systems. However, staff group members cannot destroy anyone else's file systems.

# zfs allow staff create,mount tank
# zfs allow -c create,destroy tank
# zfs allow tank
-------------------------------------------------------------
Create time permissions on (tank)
        create,destroy
Local+Descendent permissions on (tank)
        group staff create,mount
-------------------------------------------------------------
# su cindys
cindys% zfs create tank/cindys
cindys% exit
# su marks
marks% zfs create tank/marks/data
marks% exit
cindys% zfs destroy tank/marks/data
cannot destroy 'tank/mark': permission denied

Example 9-3 Delegating Permissions at the Correct File System Level

Ensure that you delegate users permission at the correct file system level. For example, user marks is delegated create, destroy, and mount permissions for the local and descendent file systems. User marks is delegated local permission to snapshot the tank file system, but he is not allowed to snapshot his own file system. So, he has not been delegated the snapshot permission at the correct file system level.

# zfs allow -l marks snapshot tank
# zfs allow tank
-------------------------------------------------------------
Local permissions on (tank)
        user marks snapshot
Local+Descendent permissions on (tank)
        user marks create,destroy,mount
-------------------------------------------------------------
# su marks
marks$ zfs snapshot tank/@snap1
marks$ zfs snapshot tank/marks@snap1
cannot create snapshot 'mark/marks@snap1': permission denied

To delegate user marks permission at the descendent file system level, use the zfs allow -d option. For example:

# zfs unallow -l marks snapshot tank
# zfs allow -d marks snapshot tank
# zfs allow tank
-------------------------------------------------------------
Descendent permissions on (tank)
        user marks snapshot
Local+Descendent permissions on (tank)
        user marks create,destroy,mount
-------------------------------------------------------------
# su marks
$ zfs snapshot tank@snap2
cannot create snapshot 'tank@snap2': permission denied
$ zfs snapshot tank/marks@snappy

Now, user marks can only create a snapshot below the tank file system level.

Example 9-4 Defining and Using Complex Delegated Permissions

You can delegate specific permissions to users or groups. For example, the following zfs allow command delegates specific permissions to the staff group. In addition, destroy and snapshot permissions are delegated after tank file systems are created.

# zfs allow staff create,mount tank
# zfs allow -c destroy,snapshot tank
# zfs allow tank
-------------------------------------------------------------
Create time permissions on (tank)
        destroy,snapshot
Local+Descendent permissions on (tank)
        group staff create,mount
-------------------------------------------------------------

Because user marks is a member of the staff group, he can create file systems in tank. In addition, user marks can create a snapshot of tank/marks2 because he has specific permissions to do so. For example:

# su marks
$ zfs create tank/marks2
$ zfs allow tank/marks2
-------------------------------------------------------------
Local permissions on (tank/marks2)
        user marks destroy,snapshot
-------------------------------------------------------------
Create time permissions on (tank)
        destroy,snapshot
Local+Descendent permissions on (tank)
        group staff create
        everyone mount
-------------------------------------------------------------

But, user marks cannot create a snapshot in tank/marks because he doesn't have specific permissions to do so. For example:

$ zfs snapshot tank/marks2@snap1
$ zfs snapshot tank/marks@snappp
cannot create snapshot 'tank/marks@snappp': permission denied

In this example, user marks has create permission in his home directory, which means he can create snapshots. This scenario is helpful when your file system is NFS mounted.

$ cd /tank/marks2
$ ls
$ cd .zfs
$ ls
snapshot
$ cd snapshot
$ ls -l
total 3
drwxr-xr-x   2 marks    staff          2 Dec 15 13:53 snap1
$ pwd
/tank/marks2/.zfs/snapshot
$ mkdir snap2
$ zfs list
NAME                   USED  AVAIL  REFER  MOUNTPOINT
tank                   264K  33.2G  33.5K  /tank
tank/marks            24.5K  33.2G  24.5K  /tank/marks
tank/marks2             46K  33.2G  24.5K  /tank/marks2
tank/marks2@snap1     21.5K      -  24.5K  -
tank/marks2@snap2         0      -  24.5K  -
$ ls
snap1  snap2
$ rmdir snap2
$ ls
snap1

Example 9-5 Defining and Using a ZFS Delegated Permission Set

The following example shows how to create the permission set @myset and delegates the permission set and the rename permission to the group staff for the tank file system. User cindys, a staff group member, has the permission to create a file system in tank. However, user lp doesnot have permission to create a file system in tank.

# zfs allow -s @myset create,destroy,mount,snapshot,promote,clone,readonly tank
# zfs allow tank
-------------------------------------------------------------
Permission sets on (tank)
        @myset clone,create,destroy,mount,promote,readonly,snapshot
-------------------------------------------------------------
# zfs allow staff @myset,rename tank
# zfs allow tank
-------------------------------------------------------------
Permission sets on (tank)
        @myset clone,create,destroy,mount,promote,readonly,snapshot
Local+Descendent permissions on (tank)
        group staff @myset,rename
# chmod A+group:staff:add_subdirectory:fd:allow tank
# su cindys
cindys% zfs create tank/data
Cindys% zfs allow tank
-------------------------------------------------------------
Permission sets on (tank)
        @myset clone,create,destroy,mount,promote,readonly,snapshot
Local+Descendent permissions on (tank)
        group staff @myset,rename
-------------------------------------------------------------
cindys% ls -l /tank
total 15
drwxr-xr-x   2 cindys   staff          2 Aug  8 14:10 data
cindys% exit
# su lp
$ zfs create tank/lp
cannot create 'tank/lp': permission denied